<!DOCTYPE html>
<html lang="zh-cn">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>异步</title>
</head>

<body>

</body>

</html>
<script>
    let a = 10;
    let b = 20;
    let c = 30;
    window.console.log(a);
    for (let index = 31; index < 35; index++) {
        window.console.log(index);
    }
    setTimeout(() => {
        setInterval(() => {
            window.console.log(b);
        }, 1000);
    }, 1000 * 5);

    for (let index = 61; index < 65; index++) {
        window.console.log(index);
    }
    setInterval(() => {
        window.console.log(c);
    }, 1000);
</script>